Virgin Olive Oil Protects the Cornea against Diabetes-Induced Damage in Rats: A Biochemical and Histological Study

Diabetes mellitus (DM) is a chronic health problem with a growing spread universally. Diabetes poses severe health complications, including neuropathy, cardiomyopathy, and ocular difficulty which is a typical complaint between diabetic subjects. Virgin olive oil is a natural product rich in phenols and other antioxidants. It is commonly recognized to protect against numerous ailments and disorders, including diabetes. The main objective of the present study was to investigate the possible protective role of virgin olive oil against diabetic induced corneal histopathological changes in streptozotocin (STZ) induced diabetic rats. Furthermore, the underlined mechanism was investigated regarding the antioxidant's capacity. Diabetes was induced by giving a single intraperitoneal (i.p.) injection of STZ (40 mg/kg bw). Twenty-four male Sprague-Dawley rats were allocated in 4 equal groups: nondiabetic control, STZ- diabetic, diabetic and olive oil (1.0 ml/100 gmbw/day), and diabetic and metformin (500 mg /kg/bw/day). The experiment design for treatment last for six weeks. Pathological examination of the corneal tissue was used to ascertain the potential protective effect of virgin olive oil against the damage associated with diabetes. The results of this study showed a glycemic and glycated hemoglobin lowering effect of virgin olive oil and metformin in STZ-induced diabetes. Moreover, olive oil and metformin reduced the lipid peroxidation product and increased the level of total antioxidants capacity. Furthermore, this study showed an ameliorative effect of olive oil on diabetic induced corneal histopathological complications. In conclusion, olive oil seemed to protect against diabetic induced changes in rat's cornea as it maintained epithelium integrity and prevented keratinization and stroma neovascularization via both controlling blood glucose level and most probably via antioxidant activity.